This invention relates to protective coatings and, more particularly, to a protective coating having a metallic alloy composition that includes a noble metal for enhanced oxidation resistance.
Components that are exposed to high temperatures, such as gas turbine engine components typically include a protective coating system having one or more coating layers. For example, turbine blades, turbine vanes, and blade outer air seals typically include a coating system to protect from erosion, oxidation, corrosion or the like, to thereby enhance their ability or maintain efficient operation of the engine.
One type of typical coating system includes a metallic coating, such as a MCrAlY coating, as a “stand-alone” coating or as a bond coat for a ceramic topcoat. The metallic coating reacts with oxygen to form an adherent oxide that protects the underlying component from corrosion. Although effective, it also is desirable to control a rate of oxidation of the MCrAlY coating to provide enhanced corrosion protection. One proposed solution is to use additive elements to control oxidation. However, some types of additive elements may diffuse and react with elements from the component to form intermetallic phases that degrade the mechanical integrity of the component or reduce the oxidation resistance of the coating.
Accordingly, there is a need for a protective coating having a composition that provides effective oxidation resistance and that can be economically manufactured.